$ git clone -n https://src.fedoraproject.org/rpms/prooftree.git /var/lib/mock/f42-build-865657-173376/root/chroot_tmpdir/scmroot/prooftree
Cloning into '/var/lib/mock/f42-build-865657-173376/root/chroot_tmpdir/scmroot/prooftree'...
$ git fetch origin b986e9992369c416c1f24e9e39bbf7f8439b8d21:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/prooftree
 * [new ref]         b986e9992369c416c1f24e9e39bbf7f8439b8d21 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b986e99 OCaml 5.3.0 rebuild for Fedora 42